Sahih al-Bukhari 56:272
Narrated Nafi' (ra):
A horse of Ibn 'Umar fled and the enemy took it. Then the Muslims conquered the enemy and the horse was returned to him during the lifetime of Allah's Messenger (ﷺ). And also, once a slave of Ibn 'Umar (ra) fled and joined the Byzantines, and when the Muslims conquered them, Khalid bin Al-Walid returned the slave to him after the death of the Prophet (ﷺ).
Reference
Sahih al-Bukhari 56:272
In-book reference
Book 56, Hadith 272
Arabic Text
قَالَ ابْنُ نُمَيْرٍ حَدَّثَنَا عُبَيْدُ اللَّهِ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما ـ قَالَ ذَهَبَ فَرَسٌ لَهُ، فَأَخَذَهُ الْعَدُوُّ، فَظَهَرَ عَلَيْهِ الْمُسْلِمُونَ فَرُدَّ عَلَيْهِ فِي زَمَنِ رَسُولِ اللَّهِ صلى الله عليه وسلم، وَأَبَقَ عَبْدٌ لَهُ فَلَحِقَ بِالرُّومِ، فَظَهَرَ عَلَيْهِمُ الْمُسْلِمُونَ، فَرَدَّهُ عَلَيْهِ خَالِدُ بْنُ الْوَلِيدِ بَعْدَ النَّبِيِّ صلى الله عليه وسلم.